Unfortunately, while annoying, there is nothing you can do.

While some retailers will refund the difference if the price drops within a certain time of purchase, BA is not one of them.

In fact, BA have no cooling off period at all that I'm aware of, at least in the UK. I'm not sure if this complies with the distant sales regulations or not... I thought for online purchases you generally had a right to cancel with 7 days.

Apparently, according to http://www.oft.gov.uk/about-the-oft/...g-regulations/

Also, as an example:

Q I recently booked tickets online for a festival in July. The next day I received an invitation to a close friend's wedding, which is happening on the same day. The vendor has a no-refund policy and refused to help me, but I seem to remember hearing about a seven-day cooling-off period for all internet sales. Is this in my head or am I just clutching at straws? Please help - failing this I'll have to eBay the tickets!
RT

A It's not all in your head and you're not clutching at straws. The Office of Fair Trading's (OFT) Distance Selling Regulations entitle all buyers of goods and services online to a cooling-off period of seven working days, calculated from the date the transaction is completed. During this period you can cancel and get a full refund, without having to give any reason at all.

There are some exceptions to the rules - goods made to a customer's specifications, for example, or perishable goods such as food or flowers - but festival tickets are not among these exemptions so the vendor is in breach of the regulations by refusing you a refund.

You will need to complain in writing and send your letter by recorded delivery to the vendor, and if it still refuses to budge you should take your complaint to the OFT and your local Trading Standards office.